The present invention relates to a coupling device having a male coupler and a female coupler. More particularly, the present invention relates to an improved coupling device having a valve at the outlet of a female coupler adapted for having a certain shut-down property to prevent a fluid from leaking out from the female coupler.
A variety of conventional coupling devices, each comprising a male coupler and a female coupler, have been introduced for practical use in industrial machines to detachably connect one fluid path to the other in a fluid supply system (e.g. of hydraulic or pneumatic system). For example, a work pallet for detachably holding one or more works to be machined by a machining center includes one or more hydraulic clamping apparatuses. A coupling device is commonly provided for connecting a hydraulic path to the hydraulic clamping apparatus for supplying a hydraulic pressure.
Referring to FIGS. 8 to 10, a conventional coupling device 100, developed by the same applicants as of the present invention, includes a male coupler 101, a female coupler 102, and a hydraulic cylinder 103.
While male coupler 101 is fixed with a plurality of bolts 104, female coupler 102 is located lower than male coupler 101 and joined to hydraulic cylinder 103 for moving forward and backward. Female coupler 102 is installed in a cylinder body 105 of hydraulic cylinder 103 and is driven by hydraulic cylinder 103, moving between a coupled position and a separated position.
Male coupler 101 has a protruded cylindrical portion provided at the lower end thereof which can be inserted into the upper end of female coupler 102. When the male and female couplers 101 and 102 are coupled to each other (see FIG. 10), both a main opening/closing valve 106 and an auxiliary opening/closing valve 107 in male coupler 101 open their hydraulic passages. When the male and female couplers 101 and 102 are separated from each other (see FIGS. 8 and 9), both main valve 106 and auxiliary valve 107 in male coupler 101 shut down their hydraulic passages.
As a valve shaft 109 of auxiliary valve 107 in the coupled position retracts in an upward direction relative to the protruded cylindrical portion, its valve body portion 110 comes into direct contact, with metal touch, with the annular tapered face of a valve seat portion 108 of auxiliary opening/closing valve 107. Therefore, auxiliary valve 107 is constituted as a seat type valve.
When the male and female couplers 101 and 102 are in the coupled position (see FIG. 10), both a main opening/closing valve 111 and an auxiliary opening/closing valve 112 in the female coupler 102 open their hydraulic passages. In the separated position (see FIGS. 8 and 9), both main valve 111 and auxiliary valve 112 shut down their hydraulic passages. As shown in FIG. 9, while main valve 111 shuts down its hydraulic passage in the separated position, the passage between a cylindrical member 113 and a shaft member 114 of auxiliary valve 112 is closed. Because shaft member 114 moves into the protruded cylindrical portion of male coupler 101 in the coupled position as shown in FIG. 10, it is difficult to constitute auxiliary opening/closing valve 112 as a seat type valve. Accordingly, auxiliary valve 112 permits its shaft member 114 to fit at its distal end into a valve face opening of cylindrical member 113 for closing the passage. The distal end of cylindrical member 113 is thus equipped with an annular seal element 115 made of a synthetic resin material to seal off the lower end of the protruded cylindrical portion of male coupler 101 in the coupled position.
When connected to a hydraulic source provided with a oil pressurizing means, such as an electric pressure pump, the system is supplied with a hydraulic oil which may contain some air. As a result, when the male and female couplers 101 and 102 are separated from each other, minute bubbles of air may be trapped in female coupler 102 and then leak out with oil from auxiliary valve 112, resulting in a loss of the hydraulic oil and polluting the environment of the coupling device.
For example, by providing a separable structure of shaft member 114 of female coupler 102, it is possible to constitute the auxiliary opening/closing valve 112 as a seat type valve like that of male coupler 101. However, the internal pressure in female coupler 102 is decreased close to an ambient pressure in the separated position, hardly pressing against the seat portion. Accordingly, the leakage of air and oil from auxiliary opening/closing valve 112 is unavoidable. In addition, because the oil of higher pressure which leaked from main opening/closing valve 111 may act on the distal end of female coupler 102 and exert a large force against shaft member 114, it is an adverse idea to decrease the diameter of shaft member 114.
It is an object of the present invention to provide a coupling device which overcomes the foregoing problems.
More specifically, it is an object of the present invention to provide a coupling device which can prevent any leakage of a fluid from an auxiliary opening/closing valve in its female coupler with a simple arrangement.
It is a further object of the present invention to provide a coupling device which seals the fluid containing air in the female coupler, even if the pressure of the fluid remains or is as low as the ambient pressure level when its two couplers are separated from each other.
The coupling device according to the present invention has a male coupler and a female coupler capable of detachably coupling with the male coupler to connect and disconnect the passage of a pressurized fluid.
Briefly stated, the present invention provides a coupling device, having a simple structure, which prevents leakage of fluid from an auxiliary valve in a female coupler. The coupling device seals fluid containing air in the female coupler, even in the pressure of the fluid remains or is as low as the ambient pressure level when the male coupler is separated from the female coupler. An annular seal, having integrally formed first and second annular seal elements, is provided in the female coupler. The first annular seal seals between a protruded cylindrical member of the male coupler and a mating cylindrical member of the female coupler. The second annular seal forms a valve body portion of the cylindrical member of the female coupler.
According to one embodiment of the present invention, there is provided a coupling device having a male coupler and a female coupler, wherein said male coupler and said female coupler fit together to connect a passage of a fluid, wherein: the male coupler includes a first valve mechanism having a protruded cylindrical member; a valve shaft axially movable in an interior of the protruded cylindrical member; a first valve body portion on the valve shaft; the valve body portion engaging and disengaging from the interior with a valve seat portion provided in the protruded cylindrical member, thereby shutting down the passage of the fluid between the protruded cylindrical member and the valve shaft; and a first spring, urging the first valve shaft toward a closed position; the female coupler includes a second valve mechanism having a main body case with an engaging bore provided therein; the engaging bore fitting with the protruded cylindrical member; a shaft member mounted in the main body case; a cylindrical member, fitted on the shaft member, axially movable and positioned opposite to a distal end of the protruding cylindrical member; a second valve body portion provided on the cylindrical member, engaging and disengaging from an inner side with a cylindrical valve face portion; the cylindrical valve face portion provided near a distal end on the shaft member, thereby shutting down the passage of the fluid between the cylindrical member and the shaft member; and a second spring, urging the cylindrical member toward a valve closed position.
According to another embodiment of the present invention, there is provided a coupling device for coupling a male coupler and a female coupler, including a male coupler main valve; a male coupler auxiliary valve a female coupler main valve; a female coupler auxiliary valve; at least one male coupler spring, urging the male coupler main valve and the male coupler auxiliary valve in a closed position; at least one female coupler spring, urging the female coupler main valve and the female coupler auxiliary valve in a closed position; the male coupler auxiliary valve being positioned at least a portion of a protruded cylindrical member; the female coupler auxiliary valve being position in at least a portion of a cylindrical member; and the protruded cylindrical member fitting into the cylindrical member when the male coupler and the female coupler are mated.
In particular, the male coupler has a first valve mechanism, including an protruded cylindrical member provided for partially inserting into the female coupler. A valve shaft is installed for axial movements in the inner side of the protruded cylindrical member. A valve body portion is provided on the valve shaft for engaging and disengaging from the inner side with a valve seat portion provided in the protruded cylindrical member to shut down the passage of a fluid between the protruded cylindrical member and the valve shaft. A spring is also provided for urging the valve shaft towards a valve closed position.
The female coupler has a second valve mechanism including a main body case having an engaging bore provided therein into which the protruded cylindrical member can be advanced. A shaft member is mounted in the main body case. A cylindrical member is fitted on the shaft member for axially sliding movements and positioned opposite to the distal end of the protruded cylindrical member. A valve body portion is provided on the cylindrical member for engaging and disengaging from the inner side with a cylindrical valve face portion provided near the distal end on the shaft member to shut down the passage of a fluid between the cylindrical member and the shaft member. A spring is also provided for urging the cylindrical member towards a valve closed position. Additionally, an annular seal element is provided on the distal end of the cylindrical member, having a first annular seal portion for sealing between the protruded cylindrical member and the cylindrical member in the coupled position, and a second annular seal portion, forming the valve body portion of the cylindrical member. First and second annular seal portions are formed integrally.
When the male coupler and the female coupler are separated from each other, the first valve mechanism in the male coupler allows the valve body portion of the valve shaft to be pressed by the spring directly on the valve seat portion of the protruded cylindrical member to shut down the fluid passage between the protruded cylindrical member and the valve shaft. The second valve mechanism in the female coupler causes the cylindrical member to be urged towards the valve closed position by the spring so that the valve body portion of the cylindrical member comes into direct contact with the cylindrical valve face portion close to the distal end of the shaft member, hence closing the fluid passage between the cylindrical member and the shaft member. The annular seal element mounted on the distal end of the cylindrical member has the annular seal portion which incorporates the valve body portion of the cylindrical member, thus increasing the shut-down effect of the second valve mechanism in the female coupler and preventing any leakage of the fluid from the second valve mechanism when the two couplers are separated.
When the male coupler and the female coupler are moved close to each other in the coupled position, the protruded cylindrical member and the cylindrical member come into direct contact with each other and the valve shaft and the shaft member come into direct contact with each other. With the valve shaft and the shaft member remaining in direct contact with each other, the protruded cylindrical member moves partially into the engaging bore in the main case of the female coupler until the annular seal portion of the annular seal element, mounted on the cylindrical member, seals between the protruded cylindrical member and the cylindrical member. The first valve mechanism in the male coupler allows the valve body portion of the valve shaft to depart from the valve seat portion of the protruded cylindrical member as resisting against the yielding force of the spring, thus opening the fluid passage between the protruded cylindrical member and the valve shaft. The second valve mechanism in the female coupler permits the cylindrical member to be pressed down by the distal end of the protruded cylindrical member and retract inwardly as resisting against the yielding force of the spring, hence opening the fluid passage between the cylindrical member and the shaft member.
According to an embodiment of the present invention, the annular seal element consisting mainly of the annular seal portion, sealing between the protruded cylindrical member and the cylindrical member in the coupled position, and another annular seal portion, incorporating the valve body portion of the cylindrical member, is provided on the distal end of the cylindrical member. The sealing effect of the second valve mechanism in the female coupler is ensured in the separated position, even when the pressure of the fluid remains or is as low as the ambient pressure level in the female coupler. Any leakage of the fluid containing air from the second valve mechanism is prevented. As a result, the loss of the fluid, such as a working oil, is avoided, the environment of the coupling device is minimally polluted, and the operational durability of the coupling device is significantly increased. As the two annular seal portions are provided on the single annular seal element, the arrangement of the distal end of the cylindrical member is simplified, thus contributing to the decrease of the overall number of the components.
The annular seal element is preferably made of an elastic rubber material. In this case, the annular seal portion (the valve body portion of the cylindrical member) of the annular seal element is elastically deformed upon coming into direct contact with the cylindrical valve face portion of the shaft member. Any leakage of the fluid or air from the second valve mechanism in the female coupler is positively prevented, even if the pressure in the female coupler is close to the ambient pressure level. Also, the valve seat portion in the first valve mechanism is preferably an annular taper face so that the valve body portion of the valve shaft comes into direct contact with the valve seat portion at metal touch. This allows the valve shaft to be urged towards the valve closed side by the yielding force of the spring when the two couplers are separated and its valve body portion comes into direct contact with the annular taper face. This structure prevents any leakage of the fluid from the first valve mechanism in the male coupler.